Method of and means for burning pulverulent fuels



May 15, 1928. 1,670,276

E. B. WORTHINGTON METHOD OF AND MEANS FOR BiJRNING PULVERULENT FUELS Filed July 9, 1920 Patented May 15, 1928.

UNITED "STATES 1,670,276 PATENT OFFICE.

EDWARD B. WOBTHINGTON, OF CLEVELAND, OHIO, ASSIGNOR TO THE M. A. HANNA COMPANY, 01 CLEVELAND, OHIO, A CORPORATION OF OHIO.

METHOD 0! AND MEANS FOR BURNING PULVERULEN '1 FUELS.

Application filed July 9,

My invention relates to improvements in method of and means for burning pulverulent fuels and has for its object the effecting of material economies in burning such fuel and disposingof the resultant slag and ash. The furnace construction herein set forth as an embodiment of my invention is one adapted primarily for the burning of low volatile ulverulent fuels, such as anthracite, coke reeze and culm, which require the maintenance of a relatively high igniting temperature.

Prior to my invention the handling of the slag and ash necessarily produced at the excessive temperatures maintained in a furnace burning pulverized fuel, has involved much care and attention on the part of the user. Frequently heavy depositsvof slag resulted in the shutdown of the furnace for removal of the slag. On the other hand, if

' means for frequent withdrawal of the slag and ash were provided and availed of, the

large accession of air during the withdrawal of the slag served to reduce the efiiciency of the furnace very materially. Again, when bottom openings were relied upon, through which the slag was designed to find ex t from the combustion chamber by gravity, 1t has been found that these openings gradually closed and slagged over, with the result that the furnace must be shut down and cleared of the accumulated slag.

My present invention has overcome these difficulties hitherto experienced, by provid' ing a sharply inclined slagging surface within the combustion chamber and suitable means, preferably afforded by an associated flushing stream of water for normally carrying away the slag and ash as it falls from the slagging surface. In addition thereto, I have provided means for deflecting the deflagrating fuel sufficiently to melt any accumulation of slag from the slagging surface, which may be brought into operation at intervals as may be required. These further means comprise a jet or jets of a suitable gaseous medium; steam being more often economically available, Which medium is angularly projected against the flame to effect a blow pipe action and temporarily subject the slagging surface to a temperature which will melt therefrom any accumulation of slag.

The method and features above adverted to, together with further details of my improvements may be more readily explained 1920. Serial No. 394,894.

by making reference to the accompanying drawlngs which illustrate in somewhat diagrammatic manner the preferred apparatus for practicing and embodying my invention, wherein Figure 1 is a composite view, partly in elevation and partly in vertical section, illustrating two furnaces and associated boilers embodying my invention, the one on the left being shown mainly in outline with the fuel feeding apparatus omitted.

Fig. 2 is another Vertical section taken at right angles to the sectional View of Fig. 1. Fig. 3 is an enlarged-detail of the air-seallng door, Flg. 4 is an enlarged fragmentary section llustrating the flushing means, and Fig. 5 is another enlarged detail showing a controlllng damper for the air supply.

Throughout the several figures of the drawings 1 have employed the same character of reference to indicate similar parts.

Figure 2 Will disclose the peculiar charnace, an air supply adapted to be pre-heated by the slag, means for sealing the flushing exit against an'influx of air, and a system of steam or air jets for deflecting the furnace flame temporarily in order to melt down any accumulated slag. The furnace in question preferably is one supplied by a downwardly directed nozzleconveying the fuel cloud in a thin sheet, wherein the exit from the combustion chamber is closely adacent to such nozzle to insure the deflagration of the fuel cloud in a broad, reverting flame which maintains the igniting temperature of the incoming fuel by directly communicated heat. While I have shown an approved type of boiler associated with my improvements, obviously, this has no necessary relation to my invention and its application in the arts.

The furnace a is surmounted by boiler b positioned above the exit flue a of the combustion chamber d. Adjacent to said flue there is positioned a nozzle e extending across the top portion of the arch d and supplied by pipes e and 6', respectively, with pulverized fuel, such as finely owdered anthracite, and with compresse air. The bottom f of the furnace is V-shaped;

being provided at either side with perforated water supply pipes 9 adapted to spray a continuous stream of water upon the inclined bottom plates i which discharge into the trough f.

Upon the right, Fig. 2, will be observed a sharply inclined slagging wall or surface h, which is beneath the normal reverting flame 1' produced by the deflagrating fuel curtain, when the furnace is in operation. It is to be noted, however, that this deflagration normally takes place in space, so that none of the side walls or surfaces of the furnace is subjected to the intense heat of the burning fuel cloud. Instead, the stack effect causes the flame z' to double back or revert adjacent to, but above the slagging surface it and before passing through the flue 0 subjects the incoming fuel cloud to an igniting temperature which is maintained with considerable uniformity, dependent, of course, upon the operating conditions of the furnace.

This result is contributed to in large measure by the close regulation of the bottom air supply through the several widely distributed openings 7' beneath the slagging surface, which may be controlled by the members j respectively pivoted to swing in front of said openings. Thus the bottom air supply may be regulated by the individual adjustment of these rotatable clo sure members j to suit the varying conditions of firing the furnace. An initial air supply is induced interiorly of the looped reverting flame; being controllable by adjusting the pivoted damper d".

Positioned within the casing it above the entering fuel cloud is a pipe in having a control valve k" adapted to supply jets of a suitable gaseous medium, such as air or steam; the latter usually being more practicable and economical to operate. These jets are employed only intermittently, as required, to deflect the reverting flame by something analogous to a blow pipe action within the combustion chamber, whereby, with the full force of the steam jets, said flame will be diverted from the full line position Z as shown in Fig. .2, to the dotted line position I, in which the accumulated slag upon the edge of the slugging surface h will be subjected to a melting temperature and drop from the mass in small streams or quantities that initially are cooled by the air supply from openings 1'' before falling into the water with which the bottom of the furnace is continuously supplied. By varying the force of these steam jets, the position of the flame may be regulated in order to melt the bulk of the slag from any portion of surface h. However, it is not necessary to use these jets except when the ac cumulation has massed a large quantity of slag which will not melt down with the ordinary firing of the furnace, or at the peak of the load carried thereby. Frequently it will not be necessary to use the jets, except at intervals of three or four days and, of course, it is preferable to operate the furnace as much as possible under normal conditions indicated by the variable load thrown on the boilers. The employment of the deflecting jets of gaseous medium, accordingly, is wholly intermittent as an auxiliary to the normal operation of the furnace. Thus by firing with increased pressure or flow of compressed air from pipe e", the flame 2' may be forced to assume a lower position with respect to the inclined slugging surface than is indicated by Z, corresponding to the initial velocity of the fuel cloud, which preferably is maintained relatively low under normal conditions. This will serve to melt the slag and cause its flow upon the sharply inclined slugging surface, from which it falls to the inclined bottom f, together with the ash produced by combustion.

Normally a relatively small flow of water is maintains-.1 upon the inclined bottom members f from the perforated pipes g at either side thereof. This water is suflicient to carry away the ash and the smaller portions of congcaling slag in a stream center iug at f and flowing in the intermediate channel thus designated to the main or discharge channel f" exterior of the furnace. A pivoted door m and stationary side wings m normally closethe exit opening of channcl f against the entrance of any appreciable quantities of air, while permitting the slag charged water to flow from the furnace without material impediment. However, when a large accumulation of slag has resnltcd from a long continued normal operation of the furnace. the steam jets 7c are thrown into use and immediately the slug commences to fall from the slugging lll'f2lt'l. to the bottom members f. valve is opened more widely to direct an adequate flushing stream of water along the bottom. sllllicicot to carry away the excess of slag and ash thus deposited. If the temperature within the combustion chamber is found to be reduced materially before all of the a cumulated slag has been reduced and carried oil. the steam jets and excessive flow of water may be shut off until the temperature has built up. when the prm-edure may be briefly repeated. and without materially atl'ccting the efficiency of the furnace operatimi.

In practice the operative will carefully watch the condition of firing and will regiilate the supply of water to a volume only suflicient to carry off the slag and ash falling to the bottom of the furnace. In this way a minimum flow of water is availed of. accompaniedby a minimum loss of heat from this source. Moreover, it is seen that the air supply is not subject to wide varia- Hit) - directing such fuel downwardly at a low tion in the operation of the furnace through the opening and closing of doors through which the ash and slag are withdrawn. Instead, the solid products of combustion are largely carried away as formed by a minimum flow of water, while the door m has an effective water seal along its bottom and only a slightly less effective air seal along 'its edges. to prevent the influx of quantities of air. The openings 7" maybe partly or entirely closed while excessive flushing is maintained, to compensate for the additional air which will then enter past the door m. This affords a most economical mode of disposing of the slag.

Having now described the preferred method and means for practicing my invention, I claim as new and desire to secure by Letters Patent, together with such departures therefrom as may be attributable merely to skill in the art, the following:

1. The herein described method of firing with pulverulent fuels, which consists in directing a cloud of such fuel downwardly within a combustion chamber, providing therewith an entering supply of air igniting said fuel, causing the deflagration to revert upwardly closely adjacent to the entering fuel and air to insure an igniting temperature and effect the normal combustion of the fuel cloud in space adjacent to a slagging surface, and directing a flow of suitable gaseous medium from time to time against the reverting flame to effect its deflection so as to melt any accumulated slag from said surface, substantially as set forth.

2. The herein described method of firing with pulverulent fuels, which consists in velocity within a combustion chamber, igniting said fuel, causing the deflagrating fuel to burn in space adjacent to an inclined slagging surface, and directing a flow of gaseous medium from time to time against the deflagrating fuel to effect its deflection so as to melt any accumulated slag from the inclined slagging surface, substantially as set forth.

3. The herein described method of firing with pulverulent fuels, which consists in directing such fuel downwardly at a low velocity within a combustion chamber, igniting said fuel, causing the defiagrating fuel to burn in space adjacent to an inclined slagging surface permitting the residues from combustion to accumulate thereon,

directing a flow of gaseous medium from time to time against the deflagrating fuel to effect the melting of any accumulated slag upon the inclined surface, and flushing the molten slag by an adjacent stream of water as said slag flows from the slugging surface, substantially as set forth.

4. The herein described method of firing, which consists in introducing a fuel continuously to the combustion chamber, igniting said fuel, causing the residues from its combustion to accumulate upon an inclined surface, deflecting the deflagrating fuel toward said surface from time to time to melt the accumulated residues thereon, the molten residues away by a flow of water as they drip from the inclined surface, substantially as set forth.

5. In a furnace of the class described, the combination with its combustion chamber, of means for directing a fuel cloud downwardly therein, an adjacent inclined slagging surface, and controllable means for deflecting the deflagrating fuel cloud to melt any accumulated slag from saidinclined surface, substantially as set forth.

6. In a furnace of the class described, the combination (with its vertical combustion chamber, of means for directing a fuel cloud downwardly therein, an adjacent inclined slagging surface, a subjacent fluid receptacle, and controllable means for deflecting the fuel cloud to melt any accumulated slag from said inclined surface and cause it to deposit in the receptacle, substantially as set forth.

-7. In a furnace of the class described, the combination with its vertical combustion chamber, of means for directing a fuel cloud downwardly therein, an opposing inclined slagging surface, means associated therewith for directing a deflecting current of steam against the fuel cloud, and further means for directing the flow of a flushing stream of Water below the inclined slagging surface, whereby the slag and ash are withdrawn from the combustion chamber, substantially as set forth.

In testimony whereof I do now aflix my signature.

EDWARD B. WORTHINGTON.

and flushing 

